initial velocity for a rigid body simulation: a ball rolling on a skew plane
There might be another solution but I don't know it. So what you could do is:

Give your object a Rigid Body &gt; Type &gt; Active, create your slope, Type &gt; Passive.

Put your object on the bottom, make sure it doesn't come across the surface, give your object a keyframe (i) &gt; Location, Rotation and Scale, enable the Rigid Body &gt; Animated option and give it a keyframe as well (put your mouse cursor over the option and press i):




Several frames later, move the cube a bit, create a second keyframe for your object, then disable the Animated option and keyframe again:



If the initial momentum is strong enough, it should work fine:


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